Study on thermal insulation and electromagnetic shielding properties of multifunctional GNS/SiBCN aerogel

Polymer-derived silicon boron carbonitride (SiBCN) aerogels exhibit outstanding application prospects in high-temperature thermal insulation and electromagnetic interference (EMI) shielding fields. Herein, graphene nanosheet (GNS) modified SiBCN composite aerogels were fabricated via freeze assembly, freeze-drying and high-temperature pyrolysis. Comprehensive characterizations were performed to systematically reveal the microstructure and phase composition of as-prepared GNS/SiBCN aerogels. Numerical simulations were implemented to investigate the effects of ambient temperature and sample thickness on the thermal insulation capacity, while experimental measurements were carried out to evaluate the EMI shielding performance of the composite aerogels. The as-synthesized GNS/SiBCN aerogels feature abundant micron-sized interconnected pores, which substantially suppress multiple heat transfer pathways inside the matrix. The material achieves an ultralow thermal conductivity of 0.03 W/(m·K), making it highly competitive for high-temperature thermal barrier applications, and a thermal insulation efficiency of 69.73% is realized under a thermal shock of 1000°C. Meanwhile, the composite aerogel delivers a total EMI shielding effectiveness as high as 23.37 dB. This work offers a facile fabrication strategy for lightweight materials integrating thermal insulation and EMI shielding functions and provides new insights for the development of multifunctional aerogels toward cutting-edge aerospace and thermal protection fields.